X-Message-Number: 19286
References: <>
Date: Sun, 16 Jun 2002 12:30:02 +0200
From: David Stodolsky <>
Subject: Re: Why the moon has round craters.

At 9:00 AM +0000 2002-06-16, George Smith wrote:
>Of course, my entire initial posting was to underline the fact that the
>current crop of lock step true believers still don't get it.  They stand on

Sorry, but this is just high school physics:

The total amount of energy, K, required to form a crater is
proportional to the volume, V, of  material excavated in
the impact.

http://www.jpl.nasa.gov/galileo/sepo/education/plansurf/plansurfiiia.html


for more advance stuff:

Researchers at the PSSRI have found that large-scale planetary impact
craters are not entirely radially symmetric, and may hold a record of
impact directions. The majority of lunar craters are circular, and it is
generally believed that no information about the impact direction is
preserved in the crater shape. Kepler crater (8.1 N, 38.0 W) is a 31
km-diameter ray crater on the Moon. It is unusual in that the rays clearly
show the impact direction. Although Kepler looks superficially circular, we
have found that there are subtle asymmetries in the crater shape that are
aligned with the impact direction shown by the rays. The asymmetries are
therefore likely to be a result of a body impacting at an oblique angle.
This result may provide us with a technique for finding impact directions
from crater morphology, and may help us to distinguish craters made by
comets from those made by asteroids

http://pssri.open.ac.uk/news/news-con.htm



As I stated earlier, you need 20 years of physics education to understand
today's advances. The last big news (1998) was that the Universe is filled
with dark energy.


dss
--
David S. Stodolsky, PhD    PGP: 0x35490763    

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